Is there some special property of render2d that means that culling doesn’t take place? I have a lot of objects parented to aspect2d and I get the same ~300fps no matter how many objects are actually within the bounds of the display region. Hiding them all boosts the fps to 2000.
Frustum culling does take place, I believe. However, the same rules apply as rendering to “render”: you should limit the number of Geoms to less than a few hundred to get reasonable performance. (300 FPS is very reasonable. Using FPS values to measure performance is a bit misleading, since the difference between 2000 FPS and 300 FPS is only 5 ms.)
What does set render2d apart is that depth testing and depth write are disabled, and two-sided rendering is enabled by default.